Forgot to add:
As well as the DSLR, I also have the Canon S70 (great little camera).
For the Queensland trip, I also bought the canon waterproof housing (WP-DC40), so that I could use the S70 out on the water. We also learnt to scuba dive, so it went doen to 20m as well with no problem (Boy, underwater photography is a whole other game). I found the video function to be really cool underwater.
So the WP-DC40 could mean that you get some rafting action shots as well.
Have a good trip